Fuel viscosity/density compensation device

Claim 1

A fuel viscosity compensating device for providing an output which may be used to regulate the output of a fuel pump based on the viscosity of the fuel which comprises: a housing including walls defining a pressure chamber and a fuel inlet; a piston located within the pressure chamber and being capable of reciprocating motion within the pressure chamber, said piston dividing the pressure chamber into a regulated pressure cavity on one side of the piston and a servo pressure chamber on the other side of the piston, said piston being sized relative to the housing walls to define a restricted orifice there between extending from the regulated pressure cavity to the servo pressure cavity to allow fuel to flow there between while undergoing a pressure decrease based on the viscosity of the fuel; a piston spring positioned to bias the piston toward the regulated pressure cavity; a pressure regulator connected to receive fuel under pressure from the fuel inlet and to deliver said fuel at a reduced pressure to the regulated pressure cavity; conduit means connected to receive fuel from the servo pressure cavity; swirl means connected to receive fuel from the conduit means for effecting a pressure reduction of the fuel flowing there through dependent upon the viscosity of fuel thereby effecting the pressure of the fuel in the servo chamber; and fuel control means connected to the piston to be displaced with the piston in response to the viscosity of the fuel to thereby provide an output representative of the fuel viscosity.